Usually, a wiring substrate has terminals formed on its main surface (front surface) for connection to a semiconductor chip (hereinafter referred to as connection terminals). In recent years, the disposition density of the connection terminals has been increasing; accordingly, the pitch between the connection terminals to be disposed has become finer. Thus, there is proposed a wiring substrate which employs the NSMD (non solder mask defined) feature in which a plurality of connection terminals are disposed within the same opening.
However, in the case where a plurality of connection terminals are disposed at a fine pitch within the same opening, solder coated on the surface of a certain connection terminal may flow to an adjacent connection terminal, potentially resulting in the occurrence of a short circuit between the connection terminals. In order to prevent flow of solder coated on the surface of a certain connection terminal to an adjacent connection terminal, insulating partition walls are provided between connection terminals (refer to, for example, Patent Document 1).